I don’t know? Who did? Did anyone ever actually say that? I highly doubt any reputable knowledgeable person in the field would have said never. Don’t confuse skepticism with derision. Skepticism over grand claims is a healthy part of science and innovation, it forces people that make those claims to actually put something into practice. Anyone that was skeptical of practicality of electric powered flight even 10 years ago was well founded in that skepticism based on all the technology available at the time.
Even today I’m still highly skeptical of the commercial viability of electric aircraft in all but niche markets. It’s probably going to be a very long time, if ever, before we see electric transcontinental or transatlantic passenger flights.